/*
 * HP Human Interface Loop Master Link Controller driver.
 *
 * Copyright (c) 2001 Brian S. Julin
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL").
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 *
 * References:
 * HP-HIL Technical Reference Manual.  Hewlett Packard Product No. 45918A
 *
 */

#include <linux/hil.h>
#include <linux/time.h>
#include <linux/interrupt.h>
#include <linux/semaphore.h>
#include <linux/serio.h>
#include <linux/list.h>

typedef struct hil_mlc hil_mlc;

/* The HIL has a complicated state engine.
 * We define the structure of nodes in the state engine here.
 */
enum hilse_act {
	/* HILSE_OUT prepares to receive input if the next node
	 * is an IN or EXPECT, and then sends the given packet.
	 */
	HILSE_OUT = 0,

	/* HILSE_CTS checks if the loop is busy. */
	HILSE_CTS,

	/* HILSE_OUT_LAST sends the given command packet to 
	 * the last configured/running device on the loop.
	 */
	HILSE_OUT_LAST,

	/* HILSE_OUT_DISC sends the given command packet to
	 * the next device past the last configured/running one.
	 */
	HILSE_OUT_DISC,

	/* HILSE_FUNC runs a callback function with given arguments.
	 * a positive return value causes the "ugly" branch to be taken.
	 */
	HILSE_FUNC,

	/* HILSE_IN simply expects any non-errored packet to arrive 
	 * within arg usecs.
	 */
	HILSE_IN = 0x100,

	/* HILSE_EXPECT expects a particular packet to arrive 
	 * within arg usecs, any other packet is considered an error.
	 */
	HILSE_EXPECT,

	/* HILSE_EXPECT_LAST as above but dev field should be last 
	 * discovered/operational device.
	 */
	HILSE_EXPECT_LAST,

	/* HILSE_EXPECT_LAST as above but dev field should be first 
	 * undiscovered/inoperational device.
	 */
	HILSE_EXPECT_DISC
};

typedef int (hilse_func) (hil_mlc * mlc, int arg);
struct hilse_node {
	enum hilse_act act;	/* How to process this node         */
	union {
		hilse_func *func;	/* Function to call if HILSE_FUNC   */
		hil_packet packet;	/* Packet to send or to compare     */
	} object;
	int arg;		/* Timeout in usec or parm for func */
	int good;		/* Node to jump to on success       */
	int bad;		/* Node to jump to on error         */
	int ugly;		/* Node to jump to on timeout       */
};

/* Methods for back-end drivers, e.g. hp_sdc_mlc */
typedef int (hil_mlc_cts) (hil_mlc * mlc);
typedef void (hil_mlc_out) (hil_mlc * mlc);
typedef int (hil_mlc_in) (hil_mlc * mlc, suseconds_t timeout);

struct hil_mlc_devinfo {
	uint8_t idd[16];	/* Device ID Byte and Describe Record */
	uint8_t rsc[16];	/* Security Code Header and Record */
	uint8_t exd[16];	/* Extended Describe Record */
	uint8_t rnm[16];	/* Device name as returned by RNM command */
};

struct hil_mlc_serio_map {
	hil_mlc *mlc;
	int di_revmap;
	int didx;
};

/* How many (possibly old/detached) devices the we try to keep track of */
#define HIL_MLC_DEVMEM 16

struct hil_mlc {
	struct list_head list;	/* hil_mlc is organized as linked list */

	rwlock_t lock;

	void *priv;		/* Data specific to a particular type of MLC */

	int seidx;		/* Current node in state engine */
	int istarted, ostarted;

	hil_mlc_cts *cts;
	struct semaphore csem;	/* Raised when loop idle */

	hil_mlc_out *out;
	struct semaphore osem;	/* Raised when outpacket dispatched */
	hil_packet opacket;

	hil_mlc_in *in;
	struct semaphore isem;	/* Raised when a packet arrives */
	hil_packet ipacket[16];
	hil_packet imatch;
	int icount;
	struct timeval instart;
	suseconds_t intimeout;

	int ddi;		/* Last operational device id */
	int lcv;		/* LCV to throttle loops */
	struct timeval lcv_tv;	/* Time loop was started */

	int di_map[7];		/* Maps below items to live devs */
	struct hil_mlc_devinfo di[HIL_MLC_DEVMEM];
	struct serio *serio[HIL_MLC_DEVMEM];
	struct hil_mlc_serio_map serio_map[HIL_MLC_DEVMEM];
	hil_packet serio_opacket[HIL_MLC_DEVMEM];
	int serio_oidx[HIL_MLC_DEVMEM];
	struct hil_mlc_devinfo di_scratch;	/* Temporary area */

	int opercnt;

	struct tasklet_struct *tasklet;
};

int hil_mlc_register(hil_mlc * mlc);
int hil_mlc_unregister(hil_mlc * mlc);
